Chondrodystrophic myotonia (Schwartz-Jampel syndrome) in South African children.

Three children with the clinical features of the Schwartz-Jampel syndrome are presented, two with classical features and the third with physical and radiological features resembling those found in the Schwartz-Jampel syndrome but myotonia could not be elicited either clinically or electrophysiologically. Various arguments are put forward for the absence of myotonic phenomena in the latter child.